Alt+Left Click doesn't select a loop of faces completely
Your topology is not clean. It's hard to say without the .blend, but the edge to the left of the right problem area for example looks suspicious, half selected and half black. Which suggests double faces or at least a double edge.



If you were able to select the left faceline in one go, it means the unselected face somehow sits on top of the line, seemingly unconnected to the rest. Remove double by default has a very tiny radius so it doesn't necessarily catch everything. And it only works on selected faces, so the culprits might not have been selected at the time. Could very well be that you accidentally created an ngon somewhere and the verts are basically on top of each other.

Clear your selection, go into Edge or Vertex Select Mode (they provide slightly different clues) and hit CTRLSHIFTALTM (Select Non Manifold). 

This shortcut selects every edge that hasn't exactly 2 faces attached to it and is likely to show you part of the trouble.

The amount of selected verts in the upper right corner will help with the diagnosis as well.